This is a UMC round marked .41 SHORT and it has a very short rim with no grove where it joins the case. 9th edition of CARTRIDGES OF THE WORLD list a 41 Short Colt which I assume is the same and describe it as a heel-based bullet. Does this mean that the bullet, not the case rim, somehow holds the cartridge in the cylinder bore and this tiny rim has little or no use?
I have never seen a cartridge rim like this, as I recall. I need a little education on this heel-base concept please.